This invention relates to a control unit for the air control system of an automotive vehicle. More particularly, this invention relates to a control-motion transmission assembly incorporated in the heating, ventilating and air conditioning system of an automotive vehicle.
Such a control unit is typically located at the dashboard in the passenger compartment of the vehicle. The control unit has a plastic housing and includes at least one manually movable actuator lever and a setting lever for transmitting the control motion from the actuator lever to an operating mechanism such as an air damper or an electrical resistor of the heating, ventilating and air conditioning (HVAC) system.
As set forth in British Patent No. 1,207,158, a particular control unit of this type includes a Bowden cable which aids in transmitting the control motion to the operating mechanism of the HVAC system. A lever device is provided for the forced transmission of the control or setting motion from the actuator lever to the point of attachment of the Bowden cable. This lever device includes a first component rotatable about a fixed axis and a second component connected to the first component via a slidable and tiltable coupling. The Bowden cable is fastened to one of the two components, the actuator lever being attached to the other of the components. A disadvantage of this sort of transmission assembly is that the operating forces are either nonuniform over the stroke of the actuator lever, whereby an easy setting motion of the actuator lever is impossible, or the transition between the actuator lever and the lever device is based on the principle of a linear guide, which results in increased wear.
In accordance with another design of a transmission assembly of the above-described type, a setting lever is mounted between guide surfaces extending in a setting direction. This design is very elaborate and consists of many parts.
In accordance with yet another design, a pivotably mounted intermediate lever is disposed between an actuator lever and a setting lever, whereby circular motion of the setting lever and linear or slightly curved motion of the actuator lever are combined. A perfectly parallel guide of the actuator lever along a guide track is thereby produced. In an extended or stretched-out position of the intermediate lever, a self-latching of the transmission assembly can be achieved.
An object of the present invention is to provide an improved control-motion transmission assembly of the above-described type.
Another, more particular, object of the present invention is to provide such an assembly in which the ease with which the actuator lever is moved is substantially uniform along the path of motion of the lever.
Another particular feature of the present invention is to provide such an assembly which exhibits a self-latching function in at least one end position of the actuator lever.